It is known that AMPA receptors widely distribute in the central nervous system and involve in learning, memory, neurological degeneration, cell death, and the like. In recent years, researches related to treatment for psychiatric and neurological diseases using AMPA receptors as targets (Patent Documents 1 to 3). In order to examine the relation between the AMPA receptors and these diseases, it is required to evaluate the expression level and the distribution of AMPA receptors in the brain. However, there are various problems in that there is no choice but to use the postmortem brains at the present time in order to examine the expression level or the like of these AMPA receptors and comparison with an able-bodied person cannot be conducted.
A molecular imaging method, for example, positron emission tomography (PET) is a method capable of visualizing the behaviors of molecules in living subjects in vivo. In order to visualize the behaviors of AMPA receptors in living subjects in vivo, hitherto, some molecular probes have been synthesized (Non-Patent Documents 1 to 3). However, from the reasons that conventional molecular probes have insufficient specific binding to AMPA receptors and low brain uptake of the probes, these molecular probes are difficult to use for in vivo imaging of AMPA receptors. Therefore, there is a demand for development of a new compound that specifically binds to an AMPA receptor and exhibits a high accumulation in the brain.    Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2012-207021    Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2010-202525    Patent Document 3: Japanese Unexamined Patent Application (Translation of PCT Application), Publication No. 2006-525292    Non-Patent Document 1: Gao M et al., Synthesis of carbon-11 and fluorine-18 labeled N-acetyl-1-aryl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline derivatives as new potential PET AMPA receptor ligands., Bioorg. Med. Chem. Lett. 2006 Apr. 15; 16(8):2229-33.    Non-Patent Document 2: Langstrom B et al., Endogenous compounds labeled with radionuclides of short half-life-some perspectives., J. Labelled Comp. Radiopharm. 2013 March-April; 56(3-4): 251-62.    Non-Patent Document 3: Arstad E. et al., Closing in on the AMPA receptor: synthesis and evaluation of 2-acetyl-1-(4′-chlorophenyl)-6-methoxy-7-[11C]methoxy-1,2,3,4-tetrahydroisoquinoline as a potential PET tracer., Bioorg. Med. Chem. 2006 Jul. 15; 14(14):4712-7.